Lift gate assembly

ABSTRACT

A lift gate assembly for trucks and the like of the type wherein the lift gate is movable between a position wherein it rests on the surface upon which the truck is standing and a position wherein the lift gate is level with the top of the truck body. The assembly comprises a frame having a pair of vertical members joined by an upper crosstie member at the level of the top of the truck body and a lower crosstie member at the level of the truck bed. The vertical members each support a stationary channel, the lift gate is provided at its corners adjacent the truck body with means slidably jointed to the stationary channels. The lift gate is raised and lowered by means of a pair of chains passing over sprockets mounted on a shaft at the top of the frame. Driving means are provided for the shaft and control means are provided for the driving means.

United States Patent 1 Brown 1 LIFT GATE ASSEMBLY [76] Inventor: DonaldC. Brown, c/o Brown Welding Shop, lnc., 311 W. South St., Botkins, Ohio45306 [22] Filed: Aug. 2, 1971 [21] App]. No.: 167,976

[52] US. Cl. 214/75 T, 187/9, 187/17, 187/95 [51] Int. Cl. B60p 1/44[58] Field of Search 214/75 G, 75 T; 187/9, 17, 94, 95

[56] References Cited UNITED STATES PATENTS 2,405,054 7/1946 Pringle214/75 T 2,701,654 2/1955 Williamsen..... 214/75 T 3,282,449 11/1966Buford 214/75 T 1,763,198 6/1930 Sprague.. 187/94 3,252,545 5/1966Quayle........ 187/9 2,146,533 2/1939 Erickson 214/75 T 3,142,396 7/1964Pauley et al 214/75 T July 24, 1973 Primary Examiner-Gerald M. ForlenzaAssistant Examiner--Lawrence J. Oresky Attorney-John W. Melville et al.

[57] ABSTRACT A lift gate assembly for trucks and the like of the typewherein the lift gate is movable between a position wherein it rests onthe surface upon which the truck is standing and a position wherein thelift gate is level with the top of the truck body. The assemblycomprises a frame having a pair of vertical members joined by an uppercrosstie member at the level of the top of the truck body and a lowercrosstie member at the level of the truck bed. The vertical members eachsupport a stationary channel, the lift gate is provided at its cornersadjacent the truck body with means slidably jointed to the stationarychannels. The lift gate is raised and lowered by means of a pair ofchains passing over sprockets mounted on a shaft at the top of theframe.-

Driving means are provided for the shaft and control means are providedfor the driving means.

7 Claims, 14 Drawing Figures i. l I

PATENIEDJUL24'975 3.147. 782

sum 1 or 7 lNVENTOR/S M440 6. aeomv ATTORNEYS 0 MEL-75$ INVENTOR/S004/440 c. awn x1 kyzmzmmgzm TTORNEYS LIFT GATE ASSEMBLY BACKGROUND OFTHE INVENTION 1. Field of the Invention The invention relates to a chaindriven lift gate assembly for a vehicle or the like, and moreparticularly to such an assembly wherein the lift gate is movablebetween a ground level position and a position level with the top of thevehicle body.

2. Description of the Prior Art In recent years, it has becomeincreasingly important to provide trucks and similar vehicles with someform of lifting device. Prior art workers have taken a number ofdifferent approaches in providing such lifting devices. A commonapproach has involved the provision on a vehicle of the same generaltype of lifting means used by the typical warehouse lift truck. Anotherapproach has been to provide a lifting floor section in association withthe truck bed. Yet another common lifting means has been a power tailgate capable of moving between ground level and the level of the truckbed.

Generally, the prior art lifting means have involved expensive hydrauliccylinders, or chains or cables having a number of flights or a twistedpath of travel. In some instances, prior art workers have used chains tofunction in part as racks, but this has required very criticaltolerances. Various screw means have also been used, but these alsorequire critical tolerances and a number of moving parts.

As a consquence, the provision of lifting means in assoication with atruck or the like has generally been expensive; has frequently requirednumerous moving parts; and has often been characterized by the locationof much of the lifting mechanism below the body of the truck where it isexposed to moisture and dirt, wear, and possible damage. Finally, priorart lifting structures have generally been limited in their movement,usually being confined to movement between ground level and the level ofthe truck bed.

The lift gate assembly of the present invention is simple inconstruction; inexpensive to manufacture; and characterized by a minimumof moving parts. The present lift gate assembly involves a simple chaindrive, using a pair of chains each having a single, straight flight.

The lift gate of the present invention is capable of moving from groundlevel to the level of the top of the truck body and hence isparticularly adapted to any sort of vehicle wherein it is desired tolift the load to a position higher than the truck bed. Such a vehicle isshown, for example, in U.S.'Pat. No. 3,207,166. Finally, the lift gateassembly of the present invention is capable of being produced as asimple frame-like assembly which may readily be applied to any suitabletype of vehicle.

SUMMARY OF THE INVENTION The lift gate assembly for trucks and the likecomprises a rectangular frame to which a tail gate or lift gate isslidably mounted. The frame comprises a pair of spaced, vertical membersjoined by an upper horizontal frame member or crosstie at the top of theframe and a lower horizontal member or crosstie at the level of thetruck bed. A stationary, vertical member of channel-shaped or C-shapedcross section is affixed to each of the vertical frame members.

In one embodiment, each of the: stationary channel shaped members hasslidably mounted thereon a movable member of channel-shaped or C-shapedcross section, by means of an intermediate roller-carrying membercaptively held in both the stationary and movable channel members. Thelift gate is pivotallyaffixed to the movable channel members and isswingable between a horizontal position and a vertical position. Byvirtue of the stationary and movable channel members and theirintermediate roller-carrying members, the lift gate is movablevertically between a position at ground level and a position at thelevel of the top of the vehicle body.

In a second embodiment, the stationary channelshaped members extendabove the top of the vehicle body. Each stationary member has aroller-carrying element slidably mounted therein. The lift gate ispivotally affixed to the roller-carrying elements and is again movablebetween a position at ground level and a position at the level of thetop of the vehicle body.

Vertical movement of the lift gate in both embodiments is accomplishedby means of a pair of chains one end of each of which is affixed to thelift gate. A rotatable shaft, bearing a pair of sprockets, is mounted atthe upper end of the frame. Each of the chains passes over one of thesprockets. Driving means is provided for the shaft and control means isprovided for the driving means. Operation of the control means willcause the lift gate to move upwardly or downwardly between its groundlevel and uppermost positions.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of atruck provided with the lift gate assembly of the present invention.

FIG. 2 is a fragmentary perspective view illustrating the rear side ofthe lift gate assembly.

FIG. 3 is a fragmentary plan view of the lift gate as sembly, with partsin cross section.

FIG. 4 is a fragmentary front elevational view of the assembly of thepresent invention, with parts in cross section.

FIG. 5 is a fragmentary elevational view of the structure of FIG. 4, asseen from the left of that Figure.

FIG. 6 is a side elevational view of the assembly of the presentinvention illustrating the lift gate in its lowermost position.

FIG. .7 is a fragmentary side elevational view similar to FIG. 6, butillustrating the lift gate in an intermediate position.

FIG. 8 is a fragmentary side elevational view similar to FIGS. 6 and 7,but illustrating the lift gate in its uppermost position.

FIG. 9 is a fragmentary, perspective, exploded view illustrating a pairof channel members and an intermediate roller-carrying member of thepresent invention.

FIGS. 10 and 11 are fragmentary plan views, partly in cross section,illustrating the lift gate control means BRIEF DESCRIPTION OF THEPREFERRED EMBODIMENTS While the lift gate assemblies of the presentinvention may be assembled during the construction of the vehicle towhich they are applied, they lend themselves well to assembly as unitarystructures, in and of themselves, and may be applied as a unit to avehicle under construction or an already existing vehicle. The type ofvehicle to which a lift gate assembly of the present invention may beapplied may be applied does not constitute a limitation on theinvention. Nor are the assemblies necessarily limited to theirapplication to a vehicle. For purposes of an exemplary showing, however,the assemblies will be illustrated as applied to a truck of the typeshown in U.S. Pat. No. 3,207,166.

In FIG. 1, the truck is generally indicated at l, and a first embodimentof the lift gate assembly is generally indicated at 2. The truck isillustrated as having a body 3 with side walls 4 and 5, a top or roof 6and a bottom or bed 7.

In general, the lift gate assembly comprises a lift gate 8 movablyaffixed to a rectangular frame. The rectangular frame comprises verticalframe members 9 and 10. The frame members 9 and 10 are joined at theupper ends by an upper crosstie or frame member 11 at the level of thetop 6 of the vehicle body and by a lower crosstie or frame member 12located at the vehicle bed 7.

For a more detailed description of the assembly of the presentinvention, reference is made to FIGS. 2 through 9, wherein like partshave been given like index numerals. As is most clearly shown in FIG. 3,the vertical frame member 9 has a generally L-shaped cross section andcomprises a rear wall portion 9a, a side wall portion 9b and a frontwall portion 90. The frame member 9 extends from the vehicle top 6 to apoint below the vehicle bed 7. The vertical frame member 10 is a mirrorimage of the frame member 9 and has a rear wall portion 10a, a side wallportion 10b and a front wall portion 10c (FIGS. 1 and 6). The uppercross tie 11 may have any suitable configuration. For purposes of anexemplary showing it is illustrated in FIGS. 4 and as having arectangular cross section. The crosstie 11 is affixed to the rear wallportion 9a of the vertical frame member 9 by spacer means 11a, so thatthe crosstie 11 is spaced slightly rearwardly of the rear wall portion90. It will be understood by one skilled in the art that the crosstie 11is similarly affixed to the rear wall a of vertical frame member 10.

The lower crosstie 12 is shown in FIGS. 4 and 5 as being directlyaffixed to the rear wall portion 9a of the vertical frame member 9. Itwill be understood that it is similarly affixed to the rear wall portion10a of the vertical frame member 10.

As is most clearly shown in FIGS. 3, 4 and 5, the forward facing surfaceof the rear wall portion 9a of the vertical frame member 9 carries achannel member 13. The channel 13 is of C-shaped cross sectionalconfiguration and extends substantially from the top to the bottom ofthe rear wall portion 9a.

As shown in FIGS. 3 through 5, the right rear corner v of the tail gate8 is affixed by pivot means 14 to a brace considerably shorter than thechannel member 13. The longitudinal opening 13a of channel member 13 andthe longitudinal opening 16a of channel member 16 face each other. Thechannel member 13 and the channel member 16 are joined together by anintermediate roller-carrying member 17.

The channel members 13 and 16 and the intermediate member 17 are mostclearly shown in FIG. 9. It will be noted that at its upper end channelmember 13 has a pair of stops 18 and 19. At the lower end of the channelmember an additional pair of stops 20 and 21 are provided. In similarfashion, channel member 16 has a pair of stops 22 and 23 affixed to itsupper end. At the lower end of this channel member there is located asimilar pair of stops 24 and 25 (see FIG. 4). With respect to all of thepairs of stops 18-19, 20-21, 22-23 and 24-25 a single stop, rather thana pair of stops, could be provided. The purpose of these stops will bedescribed hereinafter.

The intermediate member 17 comprises a rectangular plate having 8 pairsof slightly staggered rollers affixed thereto. The rollers of each pairare mounted on either side of the plate. Four of the roller pairs areindicated at 26-26a, 27-27a, 28-28a and 29-29a. The remaining fourroller pairs are indicated at 30-30a through 33-33a, only one roller ofeach pair being visible in this Figure (see also FIG. 15). Finally, theintermediate member I7 is provided with a centrally located stop 34. Asimilar stop is located on the opposite side of the intermediate memberand is shown at 35 in FIG. 3.

It is evident from FIGS. 3 and 7 that when the channel members 13 and 16are joined together by the intermediate member 17, the roller pairs26-26a, 27-27a, 28-2811 and 29-29a will be located within the channelmember 16. Similarly, the roller pairs 30 through 33 will be located inthe channel member 13. The stops 34 and 35 on the intermediate memberwill be located between channel members 13 and 16 and will be sopositioned as to contact the stops on these channel members. Thus,channel members 13 and 16 are joined together by means of intermediatemember 17, which is captively held in the channel members.

Turning to FIG. 6, 7 and 8, it will be noted that the rear wall portion10a of the frame member 10 supports a channel member 36 equivalent tothe channel member 13. The channel member 36 bears two pairs of stops,one stop of which is shown at 37 and one stop of which is shown at 38.

The other rear corner of the lift gate 8 is affixed by pivot means to abrace means 40. The pivot means 39 and brace means 40 are equivalent tothe pivot means 14 and brace means 15 of FIGS. 4 and 5. The brace means40 is affixed to a channel member 41 equivalent to channel member 16. Asis the case with channel member 16, channel member 14 is provided withan upper pair of stops, one stop of which is shown at 42 and a lowerpair of stops, one stop of which is shown at 43. Again the stops 37 and38 on channel member 36 and the stops 42 and 43 on channel member 41 maybe single stops, rather than pairs of stops, if desired.

An intermediate member 44 is illustrated in FIGS. 6 through 8 and issubstantially identical to the intermediate member 17 of FIG. 7. Theintermediate member 44 carries eight pairs of rollers and these rollerpairs are indicated at 45-45a through 52-52a. Finally, the intermediatemember 44 is provided with a pair of centrally located diametricallyopposed stops, one of which is shown at 53. The various roller pairs ofthe intermediate member 44 cooperate with the channel members 36 and 41in the identical manner described with respect to FIG. 7. The stops onthese channel members and on the intermediate member 44 also cooperatein the manner described.

From the above description it is evident that the lift gate 8 ispivotally affixed to channel members 16 and 41. These channel membersare, in turn, movably affixed to channel members 13 and 36 viaintermediate members 17 and 44, respectively. The stationary channelmembers 13 and 36 are, in turn, affixed to vertical frame members 9 and10.

FIGS. 6, 7 and 8 illustrate the operation of channel members 36 and 41and intermediate member 44 during movement of the lift gate 8. It willbe understood that channel members 13 and 16 and intermediate member 17cooperate in an identical manner. FIG. 6 illustrates the lift gate inits lowermost or ground level position. In this position, it will benoted that the stops 53 on intermediate member 44 have contacted thestops 38 on the stationary channel member 36. Thus, intermediate member44 has reached the lowest position it can attain. The channel member 41,bearing the lift gate 8, has reached its lowermost position asdetermined by the abutment of its stops 42 and the stops 53 on theintermediate member 44. Since the intermediate member 44 is captivelyheld both in channel member 36 and channel member 41, it will offersufficient support for the channel member 41 and the lift gate 8.

As will be evident from FIG. 6, if the lift gate 8 and the attachedchannel member 41 are caused to move upwardly, the lowermost stops 43 onthe channel member 41 will ultimately contact the stops 53 on theintermediate member 44. By virtue of this, as the lift gate proceedsupwardly, the intermediate member 44 will be carried upwardly with it.This is illustrated in FIG. 7, wherein like parts have been given likeindex numerals.

In FIG. 8, the lift gate is illustrated in its uppermost position,wherein it is substantially level with the top 6 Y of the vehicle body3. Again like parts have been given like index numerals. It will benoted that contact between the stops 43 on the channel member 41 and thestops 53 on the intermediate member 44 have caused the intermediatemember to be carried upwardly to its uppermost position. This uppermostposition is determined by the abutment of stops 53 on the intermediatemember and stops 37 on the channel member 36.

From the above description it will be evident that the intermediatemember 44 is capatively held in the channel members 36 and 41 and thatin all positions of the lift gate 8, at least two pairs of rollers onthe intermediate member will be in each of the channel members 36 and41.

The drive means for causing movement of the lift gate between itslowermost and uppermost positions is illustrated in FIGS. 4 and S. Ahorizontally oriented shaft 54 is rotatively supported by conventionalshaft hangers (not shown) affixed to the upper crosstie 11. At one end,the shaft carries a sprocket 55. The sprocket is, in turn, engaged by aroller chain 56. One end of the roller chain 56 is anchored to the liftgate, as at 57. The other end of the roller chain is provided with aweight 58 adapted to ride in a chain race channel 58a affixed to therear wall portion 9a of the vertical frame member 9 (see also FIG. 3).It will be noted that the rear wall portion 9a of the vertical framemember 9 has a notch 59 therein, to provide clearance for the sprocket55. A chain guard and guide 59a extends part way about sprocket andpartially into the chain race channel 58a. The chain guard may besupported from the upper cross tie 11 by brace means as shown in FIG.

It will be understood by one skilled in the art that the other end ofthe shaft 54 will carry a sprocket 55a identical to sprocket 55. Thatsprocket will, in turn, carry a roller chain 56a (similar to chain 56),one end of which is affixed to the opposite corner of the lift gate 8and the other end of which is provided with a weight equivalent toweight 58 adapted to ride in a chain race channel equivalent to channel580 and affixed to the rear wall portion of 10a of frame member 10.

From the above description it will be evident that as the shaft 54 (asseen in FIG. 5) is caused to rotate in a counter clockwise direction,the chain 56 and its counterpart 56a on the .other side of the lift gateassembly will cause the lift gate to move upwardly. Similarly, rotationof the shaft 54 in a clockwise direction will cause the lift gate 8 tomove downwardly. It will be noted in FIG. 5 that that portion of thechain 56 which performs the pulling action lies in a single, straight,vertical flight from the lift gate to the sprocket 55. The remainder ofthe chain will simply move downwardly from the sprocket 55 into thechain race channel 580 under the influence of weight 58. The same willbe true of the chain 55a on the other side of the lift gate assembly.

The driving means for causing rotation of the shaft 54 does notconstitute a limitation on the present invention. Any suitable primemover may be used. For example, the prime mover may comprise an internalcombustion engine, an electric motor or the like. A brake and sprocketassembly, driven by an electric or a hydraulic motor may be used. Forpurposes of an exemplary showing, however, the shaft is illustrated inFIGS. 1 through 3 as being driven by a low-speed, hightorque, rotatoryhydraulic power unit (generally indicated at 60) of any suitable andwell known type. In an exemplary installation, the shaft may be providedwith an appropriate gear and the hydraulic motor may be provided with asuitable worm. The hydraulic motor 60 is connected to a control valve 61by hydraulic lines 62 and 63. The valve is, in turn, connected to asource of hydraulic fluid under pressure (not shown) by input and returnlines 64 and 65. The valve 61 is affixed to the rear wall portion 9a ofthe vertical frame member 9 by suitable bracket means 66. Means areprovided on the lift gate assembly of the present invention whereby theoperator may stand on the lift gate and operate control valve 61irrespective of the position of the lift gate. These means are mostclearly shown in FIGS. 3 through 5, l0 and 11. An elongated, verticallyoriented rail 67 is pivotally affixed to the inside surface of side wallportion 90 of the vertical frame member 9, as at 68 and 69. It will benoted from FIG. 3 that the rail 67 is of T- shaped cross sectionalconfiguration with the leg of the T extending away from the insidesurface of the wall portion 9b.

Affixed to the rear surface of the rail 67 there is a lever 70 whichextends through a slot 71 (FIG. 4) in the side wall portion 9b of thevertical frame member 9. The lever 70 is pivotally affixed to a link 72which, in

turn, is affixed to the stem 66a of the valve 66. Thus, as the rail 67is caused to pivot about its pivot points, the lever 70 will pivot withit and, through the agency of link 72, will cause the valve stem 66a tomove inwardly or outwardly.

A short channel member 73 is hingedly affixed, as at 74 and 75 tohangers 76 and 77. The hangers 76 and 77 are, in turn, affixed to angleirons 76a and 77a welded to the movable channel means 16. The channelmember 73 has an elongate opening 73a therein, so positioned as toreceive the leg of the T rail 67. In addition, the channel member 73carries a handle 78.

FIG. illustrates the control mechanism in its normal position. In thisposition, no hydraulic fluid flows through valve 66 and the lift gatewill be stationary in whatever position it was stopped. In FIG. 11,manipulation of the handle 78 has caused the channel member 73 to pivotin a clockwise direction about its pivot point 74. The interaction ofthe rail 67 and the channel member 73 has caused the attached lever 70to pivot in a counter clockwise direction about the pivot points 68 and69 (FIG. 4). This has, in turn, resulted in the link 72 moving the valvestem 66a to its intermost position. This, in turn, will result in theflow of hydraulic fluid through the valve 66 and the motor 60, causingrotation of the shaft in a given direction with resultant movement ofthe lift gate in the direction dictated by the shaft rotation. It willfurther be evident from FIG. 1 1 that counter clockwise rotation of thehandle 78 and channel 73 about the pivot points 74 and 75 will causeclockwise rotation of the rail 67 and attached lever 70. This, in turn,will cause the valve stem 66a to assume its outermost position, via link72. Again, hydraulic fluid will flow through valve 66 and hydraulicmotor 60. The rotation of the motor 60 and shaft 54 will be in theopposite direction, however, resulting in the opposite movement of thelift gate 8.

As is most clearly shown in FIG. 10 and 11, that end of hanger 76 whichpasses through angle iron 76a is threaded and provided with nuts 76b and76c on either side of the angle iron. It will be understood that thesame is true with respect to hanger 77. In this way, the hangers 76 and77 may be adjusted longitudinally so that the channel member 73 properlycoacts with the T rail 67.

Finally, since the tail gate of the assembly of the present invention iscapable of movement to a position level with the top 6 of the vehicle 1,it is within the scope of the present invention to provide a covermember for the shaft 54 to protect the operator as he steps from thetail gate 8 to the vehicle top 6. Such a cover member is shown in FIG. 1and 2 at 79.

FIGS. 12, 13 and 14 illustrate another embodiment of the lift gate ofthe present invention. In this Figure, the side wall 5 and top 6 of thetruck body 3 are shown, these index numerals correspond to those used inFIG. 1. The rear wall 9a of vertical frame member 9 is also shown (againsee FIG. I) mounted on the rear wall 9a there is a vertically oriented,stationary channel member 79 which is substantially identical to thechannel member 13 of FIG. 3, except that it extends slightly above thetop 6 of the vehicle body. Slidably mounted within the stationarychannel 79 there is a roller bearing element 80 having a plurality ofslightly staggered roller pairs mounted on either side near its rearwardlongitudinal edge. These rollers are indicated at 8l-81a through 85-85a.Near the bottom of the rollercarrying element 80, there is illustratedan angle iron 86. As is most clearly shown in FIG. 14, the angle iron 86is affixed to a spacing block 87, which, in turn, is affixed to theroller-carrying element 80. The angle iron 86 has a perforation 88therein on the rear side of the angle iron there is a cylindrical sleeve89 which forms an extension of the perforation 88. The sleeve 89 isaffixed both to the angle iron 86 and to a spacing block 90 which, inturn, is attached to the roller-carrying element 80.

The angle iron 86 and spacing block 87 and 90 serve as mounting meansfor the lift gate (not shown). The lift gate will be provided with anappropriate pivot pin to be received in perforation 88 and sleeve 89.Thus, the tail gate will be swingable from a vertical position when notin use to a horizontal position, it being maintained in the horizontalposition by engagement with the horizontal flange portion of the angleiron 86.

FIG. 12 illustrates the lift gate mechanism in its lowermost position.The side of the roller-carrying element 80, opposite the side shown, isprovided with a stop member 91 indicated in dotted lines. The lowermostend of the stationary channel 79 has a cooperating stop 92 (see FIGS. 12and 14). The abutment of stop 91 against stop 92 determines thelowermost position of the assembly. It will be noted that in itslowermost position wheel pairs 81-8la and 82-82a are captively held inthe stationary channel 79, providing sufficient support for the liftgate.

FIG. 13 is similar to FIG. 12 and like parts have been given like indexnumerals. FIG. 13 differs from FIG. 12 in that it shows the lift gateassembly in its uppermost position. In this position, the lift gateitself (not shown) will be substantially level with the top 6 of thevehicle body 3.

Near its upper end, the stationary channel 79 is provided with a stop93. The uppermost position of the assembly is determined by the abutmentof the stop 93 and the spacing block 87. This is illustrated in FIG. 14.

It will be understood by one skilled in the art that in substantiallyall other respects the embodiment of FIGS. 12 through 14 issubstantially identical to the previously described embodiment. The liftgate of the assembly of FIGS. 12 through 14 will be raised and loweredby means of roller chains passing over sprockets mounted on a shaft, asdescribed with respect to FIGS. 4 and 5, for example. Again, the shaftwill be rotated by a prime mover which may be of the type described withrespect to FIG. 2. The hydraulic motor will be controlled by valve meansof the type shown at 61, which valve means will be controlled by thesame elements shown in FIGS. 10 and 11. As a consequence, the channelmember 73, hangers 76 and 77 hanger mounts 76a and 77a and controlhandle 78 are all shown in FIGS. 12 and 13, like parts having been givenlike numerals. Again, the hangers 76 and 77 are longitudinallyadjustable. The primary difference between the embodiment of FIGS. 12through 14 and the previously described embodiment being that themovable channel member 16 has been eliminated and the rollercarryingelement has been substituted for the intermediate member 17 (see FIG.9). As a consequence, the hanger mounted 76a and 77a are, in theembodiments shown in FIG. 12 and 13, affixed directly to theroller-carrying element 80. Again it will be understood that an assemblyof the type shown in FIGS. 12 and 13 will be provided at the other rearcorner of the vehicle with the other corner of the lift gate pivotallyaffixed thereto.

Modifications may be made in the invention without departing from thespirit of it.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. A lift gate assembly comprising a frame, said frame comprising a pairof vertical frame members in parallel spaced relationship, an uppercrosstie and a lower crosstie joining said vertical frame members, eachof said vertical frame members having a stationary vertically orientedchannel member affixed thereto, said stationary channel members being ofC-shaped cross section, the longitudinal openings of which face in thesame direction and away from said vertical frame members, a verticallyoriented movable channel member facing each of said stationary channelmembers, each of said movable channel members being of C-shaped crosssection the longitudinal opening of which faces said longitudinalopening of its respective stationary channel member, an intermediateroller-carrying unit joining each of said movable channel members to itsrespective one of said stationary channel members, each of saidintermediate roller-carrying units comprising a vertically oriented,elongated, plate-like structure having longitudinal sides and forwardand rearward edges, said intermediate unit having a plurality ofvertically aligned pairs of rollers adjacent said forward and rearwardedges thereof, the rollers of each pair being located on opposite sidesof said intermediate unit, said forward edge of each of saidintermediate units extending within said longitudinal opening of itsrespective one of said stationary channel members, said roller pairsalong said forward edge of said intermediate unit being located in androtatable in said last mentioned stationary channel member, saidrearward edge of each of said intermediate units extending within saidlongitudinal opening of its respective one of said movable channelmembers, said roller pairs along said rearward edge of said intermediateunit being located in and rotatable in said last mentioned movablechannel member, each of said movable channel members being verticallymovable with respect to its respective intermediate unit, each of saidintermediate units and its respective movable channel member comprisingan assembly movable vertically with respect to its respective stationarychannel member between an upper position wherein a portion of saidintermediate unit extends above said stationary channel member and aportion of said movable channel member extends above said intermediateunit and a lower position wherein a portion of said intermediate unitextends below said stationary channel member and a portion of saidmovable channel member extends below said intermediate unit, each ofsaid intermediate units being captively held and at all times having atleast two roller pairs in each of said stationary and movable channelmembers it joins, a lift gate, said lift gate being affixed to the lowerends of said movable channel members, means for vertically moving saidassemblies and lift gate between said upper and lower positions andmeans to control said moving means.

2. The structure claimed in claim 1 wherein said means to move saidassemblies and said lift gate comprises a shaft rotatively mounted on'said frame, a pair of sprockets non-rotatively affixed to said shaftnear the ends thereof, a chain engaging each sprocket, one end of eachchain being affixed to said lift gate, the other end of each chain beingfree and having a weight affixed thereto, motor means for rotating saidshaft in either direction and means for controlling said motor means.

3. The structure claimed in claim 2 including a channel shaped chainrace affixed to each of said vertical frame members, each of said chainraces being configured to receive said free and weighted end of one ofsaid chains.

4. The structure claimed in claim 2 wherein said motor means comprises ahydraulic motor, a source of hydraulic fluid under pressure connected tosaid motor, said control means for said motor comprising a valve meansin said connection between said source of hydraulic fluid under pressureand said motor to start and stop flow of said fluid through said motorand to determine the direction of said flow, and manually operablecontrol means for said valve, said control means being movablevertically with said lift gate.

5. The structure claimed in claim 1 wherein said lift gate is pivotallyaffixed to said movable channel members and swingable between ahorizontal position when in use and a vertical position when not in use.

6. The structure claimed in claim 1 wherein said upper and lowerpositions of said assemblies and said lift gate are determined bycooperating stop means on said assemblies and their respectivestationary channel members.

7. The structure claimed in claim 1 including a vehicle having a body,said body having a top, a bed, side walls, a forward end and a rearwardend, said frame being affixed to said rearward end of said body, saidlift gate being movable between a ground level position below said bedand a position level with said body top. III

1. A lift gate assembly comprising a frame, said frame comprising a pair of vertical frame members in parallel spaced relationship, an upper crosstie and a lower crosstie joining said vertical frame members, each of said vertical frame members having a stationary vertically oriented channel member affixed thereto, said stationary channel members being of C-shaped cross section, the longitudinal openings of which face in the same direction and away from said vertical frame members, a vertically oriented movable channel member facing each of said stationary channel members, each of said movable channel members being of C-shaped cross section the longitudinal opening of which faces said longitudinal opening of its respective stationary channel member, an intermediate roller-carrying unit joining each of said movable channel members to its respective one of said stationary channel members, each of said intermediate roller-carrying units comprising a vertically oriented, elongated, plate-like structure having longitudinal sides and forward and rearward edges, said intermediate unit having a plurality of vertically aligned pairs of rollers adjacent said forward and rearward edges thereof, the rollers of each pair being located on opposite sides of said intermediate unit, said forward edge of each of said intermediate units extending within said longitudinal opening of its respective one of said stationary channel members, said roller pairs along said forward edge of said intermediate unit being located in and rotatable in said last mentioned stationary channel member, said rearward edge of each of said intermediate units extending within said longitudinal opening of its respective one of said movable channel members, said roller pairs along said rearward edge of said intermediate unit being located in and rotatable in said last mentioned movable chanNel member, each of said movable channel members being vertically movable with respect to its respective intermediate unit, each of said intermediate units and its respective movable channel member comprising an assembly movable vertically with respect to its respective stationary channel member between an upper position wherein a portion of said intermediate unit extends above said stationary channel member and a portion of said movable channel member extends above said intermediate unit and a lower position wherein a portion of said intermediate unit extends below said stationary channel member and a portion of said movable channel member extends below said intermediate unit, each of said intermediate units being captively held and at all times having at least two roller pairs in each of said stationary and movable channel members it joins, a lift gate, said lift gate being affixed to the lower ends of said movable channel members, means for vertically moving said assemblies and lift gate between said upper and lower positions and means to control said moving means.
 2. The structure claimed in claim 1 wherein said means to move said assemblies and said lift gate comprises a shaft rotatively mounted on said frame, a pair of sprockets non-rotatively affixed to said shaft near the ends thereof, a chain engaging each sprocket, one end of each chain being affixed to said lift gate, the other end of each chain being free and having a weight affixed thereto, motor means for rotating said shaft in either direction and means for controlling said motor means.
 3. The structure claimed in claim 2 including a channel shaped chain race affixed to each of said vertical frame members, each of said chain races being configured to receive said free and weighted end of one of said chains.
 4. The structure claimed in claim 2 wherein said motor means comprises a hydraulic motor, a source of hydraulic fluid under pressure connected to said motor, said control means for said motor comprising a valve means in said connection between said source of hydraulic fluid under pressure and said motor to start and stop flow of said fluid through said motor and to determine the direction of said flow, and manually operable control means for said valve, said control means being movable vertically with said lift gate.
 5. The structure claimed in claim 1 wherein said lift gate is pivotally affixed to said movable channel members and swingable between a horizontal position when in use and a vertical position when not in use.
 6. The structure claimed in claim 1 wherein said upper and lower positions of said assemblies and said lift gate are determined by cooperating stop means on said assemblies and their respective stationary channel members.
 7. The structure claimed in claim 1 including a vehicle having a body, said body having a top, a bed, side walls, a forward end and a rearward end, said frame being affixed to said rearward end of said body, said lift gate being movable between a ground level position below said bed and a position level with said body top. 